The present invention relates to a method and apparatus for winding a continuously advancing yarn onto a rotating bobbin tube to form a cross wound package, and more particularly to a method and apparatus for initially threading the advancing yarn onto the bobbin tube.
DE 42 41 290 discloses a takeup apparatus, wherein an advancing yarn is wound on a tube.
In this takeup apparatus, a drivable winding spindle mounts the tube. During the winding cycle, i.e., during the winding time of the package, a yarn traversing device reciprocates the yarn on the package surface within a traverse range. Such takeup apparatus are used, for example, in spin lines to wind a plurality of yarns respectively on one package at the same time. In this apparatus, a drivable winding spindle mounts a plurality of tubes one after the other.
To obtain in a subsequent process a continuous operation for further processing such packages, the trailing yarn end of one package is knotted to the leading yarn end of the next package. For this purpose, it is necessary to form during the winding of a package a so-called transfer tail wind outside of the traverse range. To this end, the known takeup apparatus comprises a transfer tail device, wherein a yarn guide guides the yarn outside the traverse range before the actual winding cycle. To wind a transfer tail, the yarn guide is moved from a threading position to a transfer range. In the transfer range, the yarn is transferred to the traversing device. The actual winding cycle can then start.
In the known takeup apparatus, the problem arises that, depending on winding parameters, the unwound yarn length of the transfer tail wind has extremely different lengths. A further problem lies in that the length of the unwound yarn of the transfer tail does not correspond to the length of the yarn required for knotting it, but turns out to be substantially greater. This again leads to an unnecessary waste of yarn.
It is therefore an object of the invention to further develop a method and an apparatus for winding a yarn such that the wound transfer tail wind has substantially exactly the yarn length as is needed for further processing the package.